Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Help! Engine Misfire, is Dealer Milking Me?

Hi all, need help with car problem. Have 2001 Subaru Legacy GT Wagon (4 cyl 2.5 boxer engine, 5sp MT, no turbo). Have taken pristine care of this car, every scheduled maintenance and oil change per Subaru recommendations has been done. Currently has 118K miles. Last week developed slight roughness at idle and very low RPM. Engine wasn’t bucking or anything, but felt like a tiny rough shake every now and then. Didn’t notice any engine performance issues. Check engine light NOT on. Car sat for 2 days and then next day drove. This time engine roughness was just slightly more noticeable, but still almost undetectable. Again slight roughness at lower RPM’s, and seemed to lose slight power when engine would shake. Seemed to go away at higher RPMs (maybe over 1500 RPM). Later that night check engine light came on. This time it appeared roughness would occur at higher RPM’s (maybe up to 2K RPM) but roughness did not necessarily get worse in intensity.

Next day was driving on the highway and this time roughness was occuring up to 2500 or 3K RPM. Again, not shaking more roughly but just occuring now at higher RPM’s. Almost feeling as if you had dirty gas in your engine, this time loss of power was more noticeable. Since engine was now burning gas rapidly (maybe getting 50% normal mpg) after driving 1 hour on freeway so I went straight to the dealer.

Dealer did Dx scan and found engine code as misfire on cyliner 2. Was also told spark plugs were dirty and wires had high resistance. Tech recommended replace plugs/wires and do valve adjustment. I was dubious on the valve adjustment due to the high cost, so instructed dealer to have wires/plugs done.

Wires/plugs were replaced and dealer called back to say engine misfiring was worse and in fact now backfiring. I was told that valve adjustment would fix it as now it was certain it was loose or tight valves causing the issue. Tech explained that now due to better ignition from replaced wires/plugs, stronger misfire only indicated issues with the valves. I asked tech/dealer to verify wiring order to ensure they didn’t put it on wrong. Since I also had issues with my brakes and was up for 120K (30K interval) service I authorized and negotiatied a deal for the valve adjustment, 30K service, and brakes to all be done.

Next day dealer informs me after valve adjustment engine still misfiring on two. They now are saying they need to remove the engine head on cyl 2 side to do full valvetrain inspection. Now already $2K in to repairs they are asking for another $800 or so, saying valvetrain inspection and head removal costs 6.5 hours of tech time (shop labor rate $120/hr). They say it could be as easy as carbon on valve seat, chip in valve, bent valve etc - but could be as bad as chip/crack in head or internal crack. Was warned if could not be found via valvetrain inspection will have to go to machine shop to perform vacuum test to check for cylinder leaks etc.

I’m starting to get really suspicious. The original valve adjustment sounded funny to me, but I went along. After that I’m getting more suspicious as their quotes seem a bit high, and I don’t really buy the possiblities given I’ve treated this car so well and that the issues only seem to occur at less than 3K RPM. Thoughts? Is the dealer hosing me? Are they diagnosing this properly? What should I do?

One more thing re symptoms. Roughness did not occur consistenly at idle, sometimes it was there and sometimes it was not. It seemed more correlated to engine load (if there was a load and engine was at lower RPM the roughness was more consistently there).

Lastly, if at idle and there was roughness, the tacometer did not move and engine speed was consistent,

The tune up made sense, the valve adjustment ehh. Has any one tried swapping coils from one cyl to another and seeing if the misfire moves as well?? Has any one checked the fuel injector?? Have they done a compression test?? A leak down test?? Anything ??

I think there are things that can be done prior to pulling the head. Also most dealerships should have a camera they can put down the sparkplug hole to see the head with out removal.

Compression test should have been the next step after inspecting/replacing the plugs.

A malfunctioning EGR valve can cause these symptoms…But, for sure, the next thing you spend money on should be a compression test done with a mechanical gauge…

I agree regarding the compression check.

In the end it wouldn’t surprise me if your valves were out of adjustment and now one or more is burned or otherwise a problem.

So its not necessarily the case the you didn’t need a valve adjustment. Second guessing without knowing everything is tricky. But perhaps its time that you stopped taking your car to a dealer for service.

The valve lash should be inspected and adjusted as necessary every 30k miles no matter what the factory or anyone else says. For what it’s worth, years ago Subaru used to recommend an initial 1000 miles valve lash check (paid for by Subaru) and every 15k miles afterwards. That’s really not a bad policy at all; or ex-policy. The adjusters (and the reasons for lash) are the same now as they were 10, 20, or even 40 years ago.

If the lash tightens on an exhaust valve then valve face and valve seat damage can occur very quickly. Adjusting the valve lash properly after the fact may only be a short term fix and the only cure is a complete valve job and head gaskets.

Unless something has been lost in the translation between the you and the shop the engine does not have to be torn down to inspect for valve damage. A preliminary check with a vacuum gauge followed by a compression or leakdown test will reveal any problem in this area.

A somewhat loose lash adjustment on a valve can be surviveable but tight lash on a valve, especially an exhaust valve, means that you should expect the worst; either immediately or in the near future.
(When damage occurs it’s often microscopic if caught quickly. Over time that microscopic damage grows and that’s what is behind the near future remark.)

Thanks for the comments so far. I don’t think compression check was done, so was curious why that wasn’t done/recommended prior to where we are now. Yes, my issue is trying to second guess the valve adjustment. Service tech and service rep were very sure valve adjustment was the issue after replacing wires/plugs, esp since issue got worse after replacing, so that’s why I said yes to the job. I’m just miffed that they were so sure about that, conveyed that to me, and of course now are asking for more time and $$ to take the head off.

I did reading online and rarely was valve adjustment ever mentioned, most of the time it was ignition, fuel mix, or compression related. Valve adjustment isn’t totally out of the question, it just seemed odd they jumped to that so quick - seems like should have been done later on when other things were looked at first.

Right now i don’t think they’ve checked compression but they are obviously wanted to take head off now. Also, don’t know if ignition was ever checked nor was injectors ever checked. Obviously not likely EGR/fuel pump related IMO since it’s only 1 cylinder, but fuel injector is likely. Again, my thought is why didn’t they check these easier things first?


I have no answer as to why they did not do these things first. A compression test should be run for 2 reasons.

  1. The spark plugs are out so you’re in there already.
  2. Even the faintest possibility of a mechanical fault should be ruled out; otherwise, one could replace parts right and left while never solving the problem.

A vacuum gauge test only takes a minute and can be a great precursor to a compression test. It will reveal instantly if there is a tight valve lash problem although it will not reveal which valve, or plural, that it is. That is where the compression test comes in.

I’ve always run a compression test on every vehicle maintenance, tune-up, or engine driveability problem; even on late model, low miles vehicles to make sure the basic builiding block is fine.
(We had a Subaru in once that suffered such a tight lash problem (inflicted by the owner it was believed when he chose to adjust it himself and set everything at 0, a huge mistake) that both cylinder heads had to be replaced as they were trashed so badly that repairs were not feasible. This car had a measly 7k miles on it and warranty did not foot the bill. That’s a glaring example of how badly lash can affect an engine and how quickly it can occur.)

ok4450, totally agree with you. Plugs are out, easy test, why not check that. I also wonder why not check injectors and ignition coil, maybe already done but service advisor hasn’t indicated it has been done yet.

A comment upthread said why go to dealer? Fair point, but I’m new to the area so don’t know any good mechanics, and to be honest with engine misfire I wanted to have someone that really knows Subaru engines well to diagnose. In this case, obviously doubts exist if this is going to fix it but hoping I can get it fixed with minimal cost.

What the dealer has done so far in an effort to solve this issue seems reasonable to me. Other Subaru owners have had issues like this also. Fixes have included replacing the coil, EGR valve, O2 sensor, or the cam sensor. I think some have cleaned the engine grounds and solved the issue also. Some others have used Seafoam to clean out the cylinders with success. Here is a link to a Soob site that may be able to help you more. Just like this site, there are some real good techs there also.

I agree with the spark plugs and the valve adjustment, not so much with the plug wires. Plug wires always have resistance, they are designed that way. I agree that a compression test should have been done.

What I don’t understand is why you didn’t take the car out for a spin yourself between each round of maintenance instead of taking the dealers word. And, if the misfire got worse, I strongly suspect the mechanic did something wrong and he should have gone back and rechecked his work before moving on to the next step.

If this shop has to physically remove a cylinder head and/or send it out to an auto machine shop to determine if there’s a valve problem then their methodogy is suspect; at least in my opinion.

Keith is also correct about the wires having resistance in them. That’s normal and you have to go back many decades to find wires with little or no resistance. Resistance wires are used to minimize radio static, both in your car and the cop car in the next lane. :slight_smile:

“Now already $2K in to repairs they are asking for another $800”

All for guesswork…At a dealership, you pay to have your car FIXED…You should not pay for their fishing expeditions…

“Lets try this and see if it works” is NOT how professional mechanics operate…The fact that they have not yet performed a compression test screams incompetence…

Thanks for all the comments so far. First off, I haven’t taken the car out for a drive since this whole thing has been made more difficult by the fact that I was on a road trip when this happened. I left the car at the dealer while I took a rental out to continue the road trip. Update from today:

Mechanic finally wised up and did compression test. Since no issues with compression apparently they went back to the fuel injectors. Mechanic said originally they did electric test to see ground and hot on the injectors and didn’t find any issues, but after doing some more “tests” they found the misfiring cylinder had a “dry plug”. They switched injectors to cylinder 4 and found cylinder 4 misfiring, thus they now claim to have found the source which is cylinder #4.

Dealer is suggesting I replace both injectors on that side (apparently they say in their experience if one goes on that side, the other often goes too), and also do an injector clean for $160 which they say is a foam clean they use on the throttle body, throttle body intake, and injectors themselves. So here’s where I’m at and a few questions I have:

  1. Is there any way to make the dealer guarantee this will fix it? I’m just looking for them to own up to finding the problem instead of “fishing” for the cause at my expense (as another poster stated)?

  2. I now believe the valve adjustment was a bit unnecessary. Certainly I’m sure I’ve benefited from this job, but it was unnecessary. I had the service advisor go talk to the mechanic why they jumped to the valve adjustment and they said since they originally tested the injectors electronically (not sure if this is just a simple resistance test) they thought given the age/mileage (2001, 118K miles) of the vehicle they “recommended” the valve adjustment as they thought it would fix it. I’m a bit annoyed their story has gone from “this will certainly fix it” to “we simply recommended it given the age/mileage”. Should the dealer pay for this? Pay for half?

  3. What should I do going forward? For sure need to replace the 1 bad injector, but what about the other on the same side (again Subaru flat/boxer 4)? Injector clean? I’m leaning towards replacing both but simply throwing a $5 bottle of cleaner in the gas tank. Do you all agree?

I’m going to call the dealer on Monday AM and speak to the service director. This whole thing has been a major messup and I’m not very happy about how all of this has occurred. Thank you all very much for your help!

Ford, GM and Chrysler stopped building cars that required periodic valve adjustments around 1960…You would think 50 years later, everyone would have caught up…

See if some guy like me who has no formal training said, fuel injector. Why can’t the “mechanic”?? Answer these guys don’t know jack, they read computers and have idea about the basics. Really makes me mad to be honest. Any way, I say replace the one injector and never go back to this dealer. I would also try to negotiate a lower out the door price. What would this guy have done if you said ok to the head job, only to still have the miss when he put it back together ??

Ps the injector cleaning is crap, I can’t belive they are still trying to milk you out of more money.

Did they by chance provide these compression readings to you and write them down? You would be surprised at how many mechanics state that a bad reading is actually a good one. If everything is as it should be the readings should be in the 180 PSI range, give or take a bit, and similar across all cylinders.

Valve lash adjustments are a normal maintenance procedure so that is something that a customer should pay for.
Offhand, it does sound like a bit of a fishing expedition but it would be interesting to know if the lash was actually off on 1 or more valves.
If you meet with the service manager, keep it politely firm as the service manager will likely have no knowledge of what has gone on with your car up to this point. He, or she, does have the ability to reimburse some or all of the bill as a PR move and/or get the car back into the shop as a no charge to you deal.

Jeez, my 1950 Harley panhead rolled out of the factory with hydraulic lifters. (second year for them)
Sixty-two years later people are wrestling with a 75 year old problem due to solid lifters.

I would be extremely skeptical that an induction/injector cleaning is going to accomlish anything; even if they do it by going the high dollar route.

Sorry I can’t be of more help but without car in hand and some of the unknown details it can be tough to figure something like this out.

You can do a simple resistance test to see if the coil resistance of the injector is ok. It doesn’t mean the injector absolutely is ok but it is a very good sign at least and it should open when activated. If the shop missed an open coil on the injector after the amount of time already spent in the search for the trouble then that doesn’t play to well. As far as replacing both injectors I would pass on doing that. If the other one does go bad in the future you will have a good idea where to immediately look for the trouble if it does happen and it won’t leave you stranded. I would also pass on the cleaning. If you want to you can use some additives like Techron added to the tank for a lot less money. Hopefully the shop will give you at least an adjusted price for the needless valve adjustment.